1. Field of the Invention
The present invention relates to an active matrix display device in which input of a video signal to a pixel can be controlled by a driver circuit.
2. Description of the Related Art
In an active matrix display device, a switching element and a display element are provided in each of hundreds of thousand to millions of pixels arranged in matrix. Since application of voltage or supply of current to the display element is held to some extent by the switching element after a video signal is input to the pixel, the active matrix display device can be flexible on enlargement and high definition of a panel and has become the mainstream of future display devices.
There are a scan line driver circuit and a signal line driver circuit as typical examples of a driver circuit included in the display device. A plurality of pixels in one line or a plurality of lines are selected at one time by a scan line driver circuit. In addition, input of video signals to the pixels included in the selected line is controlled by a signal line driver circuit.
These scan line driver circuit and signal line driver circuit need driving at high frequency. In particular, while pixels of respective lines are selected by the scan line driver circuit, the signal line driver circuit needs to input video signals to all the pixels in the lines. Thus, driving frequency of the signal line driver circuit is extremely higher than that of the scan line driver circuit. For example, in the case of a VGA active matrix display device, driving frequency of a signal line driver circuit generally needs to be approximately 25 MHz. Further, in recent years, the number of pixels in one line of an active matrix display device has been increased because an image with higher definition, higher resolution and more gray-scales is displayed. Therefore, the signal line driver circuit needs driving at higher speed, and there has been a problem in that power consumption is high due to high driving frequency.
In view of the foregoing problem, Reference 1 (Japanese Patent No. 3338259) discloses a liquid crystal display device in which pieces of display data corresponding to adjacent two scan lines are compared with each other and transmission of the pieces of display data to the signal line driver circuit is not performed when the pieces of display data correspond to each other in order to suppress power consumption of a signal line driver circuit.
Further, Reference 2 (Japanese Patent No. 3593392) discloses a liquid crystal display device in which a wiring between a control IC and a signal line driver circuit is made shorter by providing the control IC so that output pins to the signal line driver circuit are close to the signal line driver circuit, so that power consumption due to wiring capacitance is suppressed.